BlackRock CEO Larry Fink isasking leaders of the world's biggest companies to say how they'llspend extra cash from the U.S. tax overhaul.

“What will you do with increasedafter-tax cash flow, and how will you use it to create long-termvalue?” Fink said in his annual letter to CEOs, posted on the assetmanagement company's website Tuesday. Companies have aresponsibility to explain to shareholders how “major legislativeand regulatory changes” will impact their long-term growthstrategies, Fink said.

Companies including BlackRockare expected to benefit from changes in the U.S. tax plan. Theworld's largest asset manager will see its effective tax rate fallto 23% from about 31%. BlackRock plans to use money from the taxbreak potentially for share buybacks and to pay out dividends, ittold shareholders on a Jan. 12 earnings call.

The company also said on thecall that it would look at possible future investmentopportunities, such as more aggressively seeding or co-investing innew products, as a result of the tax reform.

Over the years, Fink has pushedcompanies to explain their strategies for future growth. In theletter this week, he said that businesses should understand howstructural trends, including slow wage growth and climate change,could impact their potential to expand over time.

BlackRock, which surpassed $6trillion in assets in the fourth quarter of 2017, continues to seeits influence increase with the rise of passive investing. Finksaid in the letter that BlackRock plans to double the size of itsinvestment stewardship team over the next three years. He alsonamed Barbara Novick, vice chairman and co-founder of BlackRock, tooversee the firm's investment stewardship efforts.

The New York Times reportedearlier Tuesday on Fink's letter encouraging companies tocontribute to society.

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